UC Irvine

The lipid of the outermost layer of the skin is confined largely to the extracellular spaces surrounding the corneocytes of the stratum corneum where it forms a multilamellar adhesive matrix to act as the major permeability barrier of the skin. Knowledge of the molecular architecture of these intercellular domains is important for understanding various skin pathologies and their treatment, percutaneous drug delivery, and the cosmetic maintenance of the skin. We have surveyed by X-ray diffraction the structure of the intercellular domains and the extracted lipids of murine stratum corneum (SC) at 25, 45, and 70 degrees C which are temperatures in the vicinity of known thermal phase transitions [Rehfeld, S. J., & Elias, P. M. (1982) J. Invest. Dermatol. 79, 1-3]. The intercellular domains produce lamellar diffraction patterns with a Bragg spacing of 131 +/- 2 A. Lipid extracted from the SC and dispersed in excess water does not produce a simple lamellar diffraction pattern at any temperature studied, however. This and other facts suggest that another component, probably a protein, must be present to control the architecture of the intercellular lipid domains. We have also obtained diffraction patterns attributable to the protein envelopes of the corneocytes. The patterns suggest a beta-pleated sheet organizational scheme. No diffraction patterns were observed that could be attributed to keratin.